The present invention relates to a component mounting apparatus and method for mounting, on a circuit board, electronic components in which bumps are formed on the lower surface thereof.
As a method of mounting electronic components such as semiconductor elements on a circuit board, there has been used a mounting method in which a semiconductor package having semiconductor elements mounted on a resin substrate is mounted on the circuit board by a solder bonding method using solder bumps. In the solder bonding method of bonding the electronic components onto the circuit board using the solder bumps, the bonding is generally conducted in such a manner that the solder bumps are landed onto electrodes formed on the circuit board in the state that an auxiliary substance for soldering such as a flux or a solder paste is supplied to the solder bumps. For this reason, a paste transfer device for transferring the flux or the solder paste is disposed in such a component mounting apparatus for the semiconductor package (see, Patent Document 1 for example). In the example shown in Patent Document 1, a paste coating film having a predetermined thickness is formed on an outer periphery of a rotatable roller, and solder bumps are brought into contact with the past coating film by allowing the solder bumps to be in contact with the coating film, thereby coating the solder bumps with the paste.                Patent Document 1: JP-A-2000-022394        
Incidentally, components simultaneously mounted on the same circuit board by a component mounting apparatus are not always of the same type, but sometimes different types of components may be mounted on the same circuit board. For example, in the case where a plurality of semiconductor packages are laminated onto each other on the circuit board, optimal quantities of flux to be transferred onto the semiconductor packages are different from each other, and thus a paste transfer device needs to form flux coating films having different thicknesses at the same time. Additionally, in the case where the types of the components to be mounted are changed, it is necessary to adjust the thicknesses of the coating films to have optimal thicknesses in correspondence to the components.
However, since the known paste transfer device including the above-mentioned example disclosed in Patent Document 1 cannot form coating films having arbitrarily different thicknesses at the same time, bumps cannot be coated with an optimal amount of the flux at the time of transferring the flux thereto. For this reason, excessively insufficient amount of flux is applied depending on the type of components, thereby enabling to acquire a satisfactory soldering result.